1. Field of the Invention
The present invention relates to a process for the incremental enrichment of deuterium and/or tritium in a material which is suitable for the isotope exchange of deuterium and tritium with hydrogen, as well as to an arrangement for the implementation of the process.
The formation of deuterium, D.sub.2, and tritium, T.sub.2, is not only of significance for the nuclear fusion technology, in which deuterium and tritium serve as "fuels" and which are fused to helium under the output of energy. There is also known the utilization of deuterium in nuclear reactors moderated with heavy water, in which D.sub.2 O is employed as the moderator. Tritium is applied in the production of the luminescent pigments, for example, for luminescent paints, as well as for components in the gas filling of fluorescent lighting tubes and in the production of lightning arresters. Moreover, tritium is employed as a target for beam modulation in particle accelerators. In addition thereto, tritium serves for the marking of chemical compounds, for example, in the field of biochemistry.
Deuterium is contained in basic hydrogen and in water with 0.015 At %; in the hydrogen overwhelmingly as HD, in water in the form of HDO. Tritium is present in basic hydrogen only in disappearingly low concentrations; however, it is obtained for instance, as a byproduct during the operation of nuclear reactor installations, particularly in heavy water reactors and high-temperature reactors, as well as during the reconditioning of spent nuclear fuel elements. Inasmuch as tritium is radioactive and is directly taken up in the bio-cycle in the form of HTO, even minute quantities of tritium which are produced during the neutralizing of nuclear reactor installations, cannot remain unnoticed. For the neutralizing of the encountered tritium it is known to enrich and bond tritium in water.
2. Discussion of the Prior Art
Different processes are known for the enrichment of deuterium or tritium in hydrogen and water hereby having reference to K. M. Mackay et al "Deuterium and Tritium", in "Comprehensive Inorganic Chemistry", Volume 1, Pergamon Press, New York, 1973, pages 77 through 84; as well as NUKEM 500, "Herkunft, Handhabung and Verbleib von Tritium" RSI-510 321/196-SR 165, Febraury 1980. For example, an enrichment is achieved through the distillation of liquid hydrogen at a temperature of about 23.degree. K. or through the distillation of water at 70.degree. C. and under a vacuum. Hydro-electrolysis is known as a process with a high separating factor; thereof, in the same manner as with the distillation of hydrogen, in addition to meeting increased safety demands (high degree of sealing, explosion protection), there must also be covered a significant energy demand with regard to the enriched quantity of deuterium or tritium. The last is, above all, the instance inasmuch as it is necessary to commence with a low initial concentration of deuterium and tritium in water. In addition thereto, also known are processes in which deuterium and tritium are enriched in water through an isotope exchange in the liquid phase; referring to H. J. Fiek et al, "Tritium-Anreicherung durch Isotopenaustausch zwischen Wasserstoff und Wasser, mittels hydrophoben Katalysators fuer die Kernbrennstoff-Wiederaufbereitung", Chem.-Ing.-Techn. 52, 1980, pages 892 through 895. However, the exchange speeds in such a process are relatively slow, even with the utilization of catalysts. Moreover, currently known catalysts evidence a high susceptibility to disruption.
A heavy water recovery through the utilization of ammonia, NH.sub.3, is mentioned in the KWU-Report, No. 32, April 1980, page 9. The heavy water is recovered through a monothermal ammonia-hydrogen isotope exchange. In such a process, disadvantageous is the high energy demand, which is particularly generated during the employed electrolytic ammonia fission, and which is required for the subsequent ammonia synthesis. Also the yield for the exchanged deuterium remains low during an ammonia-water isotope exchange.